/*

** This module interfaces SQLite to the Google OSS-Fuzz, fuzzer as a service.

** (https://github.com/google/oss-fuzz)

*/

#include <stddef.h>

#if !defined(_MSC_VER)

# include <stdint.h>

#endif

#include <stdio.h>

#include <string.h>

#include "sqlite3.h"

#if defined(_MSC_VER)

typedef unsigned char uint8_t;

#endif

/* Global debugging settings.  OSS-Fuzz will have all debugging turned

** off.  But if LLVMFuzzerTestOneInput() is called interactively from

** the ossshell utility program, then these flags might be set.

*/

static unsigned mDebug = 0;

#define FUZZ_SQL_TRACE       0x0001   /* Set an sqlite3_trace() callback */

#define FUZZ_SHOW_MAX_DELAY  0x0002   /* Show maximum progress callback delay */

#define FUZZ_SHOW_ERRORS     0x0004   /* Print error messages from SQLite */

/* The ossshell utility program invokes this interface to see the

** debugging flags.  Unused by OSS-Fuzz.

*/

void ossfuzz_set_debug_flags(unsigned x){

  mDebug = x;

}

/* Return the current real-world time in milliseconds since the

** Julian epoch (-4714-11-24).

*/

static sqlite3_int64 timeOfDay(void){

  static sqlite3_vfs *clockVfs = 0;

  sqlite3_int64 t;

  if( clockVfs==0 ){

    clockVfs = sqlite3_vfs_find(0);

    if( clockVfs==0 ) return 0;

  }

  if( clockVfs->iVersion>=2 && clockVfs->xCurrentTimeInt64!=0 ){

    clockVfs->xCurrentTimeInt64(clockVfs, &t);

  }else{

    double r;

    clockVfs->xCurrentTime(clockVfs, &r);

    t = (sqlite3_int64)(r*86400000.0);

  }

  return t;

}

/* An instance of the following object is passed by pointer as the

** client data to various callbacks.

*/

typedef struct FuzzCtx {

  sqlite3 *db;               /* The database connection */

  sqlite3_int64 iCutoffTime; /* Stop processing at this time. */

  sqlite3_int64 iLastCb;     /* Time recorded for previous progress callback */

  sqlite3_int64 mxInterval;  /* Longest interval between two progress calls */

  unsigned nCb;              /* Number of progress callbacks */

  unsigned execCnt;          /* Number of calls to the sqlite3_exec callback */

} FuzzCtx;

/*

** Progress handler callback.

**

** The argument is the cutoff-time after which all processing should

** stop.  So return non-zero if the cut-off time is exceeded.

*/

static int progress_handler(void *pClientData) {

  FuzzCtx *p = (FuzzCtx*)pClientData;

  sqlite3_int64 iNow = timeOfDay();

  int rc = iNow>=p->iCutoffTime;

  sqlite3_int64 iDiff = iNow - p->iLastCb;

  if( iDiff > p->mxInterval ) p->mxInterval = iDiff;

  p->nCb++;

  return rc;

}

/*

** Disallow debugging pragmas such as "PRAGMA vdbe_debug" and

** "PRAGMA parser_trace" since they can dramatically increase the

** amount of output without actually testing anything useful.

*/

static int block_debug_pragmas(

  void *Notused,

  int eCode,

  const char *zArg1,

  const char *zArg2,

  const char *zArg3,

  const char *zArg4

){

  if( eCode==SQLITE_PRAGMA

   && (sqlite3_strnicmp("vdbe_", zArg1, 5)==0

        || sqlite3_stricmp("parser_trace", zArg1)==0)

  ){

    return SQLITE_DENY;

  }

  return SQLITE_OK;

}

/*

** Callback for sqlite3_exec().

*/

static int exec_handler(void *pClientData, int argc, char **argv, char **namev){

  FuzzCtx *p = (FuzzCtx*)pClientData;

  int i;

  if( argv ){

    for(i=0; i<argc; i++) sqlite3_free(sqlite3_mprintf("%s", argv[i]));

  }

  return (p->execCnt--)<=0 || progress_handler(pClientData);

}

/*

** Main entry point.  The fuzzer invokes this function with each

** fuzzed input.

*/

int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {

  char *zErrMsg = 0;       /* Error message returned by sqlite_exec() */

  uint8_t uSelector;       /* First byte of input data[] */

  int rc;                  /* Return code from various interfaces */

  char *zSql;              /* Zero-terminated copy of data[] */

  FuzzCtx cx;              /* Fuzzing context */

  memset(&cx, 0, sizeof(cx));

  if( size<3 ) return 0;   /* Early out if unsufficient data */

  /* Extract the selector byte from the beginning of the input.  But only

  ** do this if the second byte is a \n.  If the second byte is not \n,

  ** then use a default selector */

  if( data[1]=='\n' ){

    uSelector = data[0];  data += 2; size -= 2;

  }else{

    uSelector = 0xfd;

  }

  /* Open the database connection.  Only use an in-memory database. */

  if( sqlite3_initialize() ) return 0;

  rc = sqlite3_open_v2("fuzz.db", &cx.db,

           SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | SQLITE_OPEN_MEMORY, 0);

  if( rc ) return 0;

  /* Invoke the progress handler frequently to check to see if we

  ** are taking too long.  The progress handler will return true

  ** (which will block further processing) if more than 10 seconds have

  ** elapsed since the start of the test.

  */

  cx.iLastCb = timeOfDay();

  cx.iCutoffTime = cx.iLastCb + 10000;  /* Now + 10 seconds */

#ifndef SQLITE_OMIT_PROGRESS_CALLBACK

  sqlite3_progress_handler(cx.db, 10, progress_handler, (void*)&cx);

#endif

  /* Set a limit on the maximum size of a prepared statement */

  sqlite3_limit(cx.db, SQLITE_LIMIT_VDBE_OP, 25000);

  /* Limit total memory available to SQLite to 20MB */

  sqlite3_hard_heap_limit64(20000000);

  /* Set a limit on the maximum length of a string or BLOB.  Without this

  ** limit, fuzzers will invoke randomblob(N) for a large N, and the process

  ** will timeout trying to generate the huge blob */

  sqlite3_limit(cx.db, SQLITE_LIMIT_LENGTH, 50000);

  /* Bit 1 of the selector enables foreign key constraints */

  sqlite3_db_config(cx.db, SQLITE_DBCONFIG_ENABLE_FKEY, uSelector&1, &rc);

  uSelector >>= 1;

  /* Do not allow debugging pragma statements that might cause excess output */

  sqlite3_set_authorizer(cx.db, block_debug_pragmas, 0);

  /* Remaining bits of the selector determine a limit on the number of

  ** output rows */

  cx.execCnt = uSelector + 1;

  /* Run the SQL.  The sqlite_exec() interface expects a zero-terminated

  ** string, so make a copy. */

  zSql = sqlite3_mprintf("%.*s", (int)size, data);

#ifndef SQLITE_OMIT_COMPLETE

  sqlite3_complete(zSql);

#endif

  sqlite3_exec(cx.db, zSql, exec_handler, (void*)&cx, &zErrMsg);

  /* Show any errors */

  if( (mDebug & FUZZ_SHOW_ERRORS)!=0 && zErrMsg ){

    printf("Error: %s\n", zErrMsg);

  }

  /* Cleanup and return */

  sqlite3_free(zErrMsg);

  sqlite3_free(zSql);

  sqlite3_exec(cx.db, "PRAGMA temp_store_directory=''", 0, 0, 0);

  sqlite3_close(cx.db);

  if( mDebug & FUZZ_SHOW_MAX_DELAY ){

    printf("Progress callback count....... %d\n", cx.nCb);

    printf("Max time between callbacks.... %d ms\n", (int)cx.mxInterval);

  }

  return 0;

}